Two-Level Mobility Reference Signal Configuration

ABSTRACT

According to an aspect, one or more network nodes of a wireless communication system sends, to a wireless device operating in the wireless communication system, mobility reference signal (MRS) configuration information, the MRS configuration information specifying one or more parameters for each of a plurality of MRS configurations. The network node subsequently sends, to the wireless device, an activation command indicating that at least a first one of the MRS configurations is to be used by the wireless device, the activation command including an index identifying the first one of the MRS configurations from among the plurality of MRS configurations. The wireless device receives the MRS configuration information and the activation command. The wireless device searches for at least one MRS specified by the first one of the MRS, responsive to the activation command and performs at least one measurement on the at least one MRS.

TECHNICAL FIELD

The present invention generally relates to a method in one or morenetwork nodes of a wireless communication system, a method in a wirelessdevice operating in a wireless communication system, an arrangement ofone or more network nodes of a wireless communication system and awireless device of a wireless communication system and particularlyrelates to efficiently handling the configuration of mobility referencesignals or measurement reference signals.

BACKGROUND

Overall requirements for the Next Generation (NG) architecture (see TR23.799, Study on Architecture for Next Generation) and, morespecifically the NG Access Technology (see TR 38.913, Study on Scenariosand Requirements for Next Generation Access Technologies) will impactthe design of the Active Mode Mobility solutions for the new RAT (NR)(see RP-160671, New SID Proposal: Study on New Radio Access Technology,DoCoMo) compared to the current mobility solution in Long Term Evolution(LTE). Some of these requirements include the need to support networkenergy efficiency mechanisms, the need to account for futuredevelopments, and the need to support a very wide range of frequencies(up to 100 GHz).

In the context of Neighbor-cell Relation (NR) handover, a measurementframework can be used to support dynamic network-triggered MobilityReference Signal (MRS) measurement and reporting, and/or periodic MRSmeasurement and event based reporting (as in LTE). MRS may also standfor a Measurement Reference Signal. FIG. 1 shows a source access node70, a target access node 80 and a user equipment (UE) 50 in the contextof downlink measurement based handover. Under normal circumstances, userdata and an MRS configuration may be exchanged between the UE 50 and thesource access node 70. The MRS configuration messaging in the example ofFIG. 1 is performed at the RRC level, or at Level 3 (L3). Upon a beamswitch trigger, MRS measurements are made by the UE 50. Optionally, anMRS configuration and an activate measurement command are sent to fromthe source access node 70 to the UE 50. After measurements of downlinkreference signals are reported by the UE 50 to the source access node70, a handover decision is made by the source access node 70. A handovercommand can then be sent as a Radio Resource Control (RRC) connectionreconfiguration message from the source access node 70. A handovercommand can also be implicitly indicated by an uplink grant message fromthe target access node 80.

Upon the reception of an RRC reconfiguration message or the best beamdetection, the UE 50 contacts the target access node 80 using an UplinkSynchronization Signal (USS), which may be coupled with the MRS sequenceof the target beam/cell/node, so that the selected USS can be used toindicate the detected best beam. The USS also serves as an uplink timingreference since the UE 50 needs uplink time synchronization whenchanging access nodes. USS has a similar design as Physical RandomAccess Channel (PRACH) preamble in LTE and is intended for the uplinktiming advance (TA) calculation, uplink frequency offset estimation anduplink beam identification. As a response or a subsequent message to theUSS, the target access node 80 sends an uplink grant, including the TAto establish uplink synchronization with the target access node 80.

As an alternative to the downlink measurement based handover, therecould be uplink measurement based handover relying on the sameprinciples, as shown in FIG. 2. This may involve the source access node70 optionally sending a USS configuration and a USS activation commandto the UE 50. The USS is used to indicate a detected test beam and toserve as an uplink timing reference. The source access node 70 and/orthe target access node 80 perform measurements on signals and thendetermine the best beam. Yet, in this case, the beam switch command isan MRS, transmitted on a time/frequency resource indicated in the USSconfiguration message.

However, it is recognized herein that the current use of MRSconfiguration in these instances is not optimal, because the UE 50 maynot need to measure/report all the configured MRSs all of the time.Also, the UE 50 may not have a sufficient time budget to be reconfiguredat the RRC level for every MRS modification or configuration.

SUMMARY

Embodiments of the present invention relate to NG networks, includingthe fifth generation of cellular networks (5G). In particular, theembodiments relate to how to efficiently handle the configuration ofMRSs. The embodiments provide for a more efficient MRS configurationprocedure and signaling by means of a two-level MRS configuration. Thetwo-level MRS configuration includes one or more network nodes sendingMRS configuration information for multiple MRS configurations to awireless device and then subsequently sending an activation commandindicating one of the MRS configurations. Advantageously, the MRSconfiguration information specifies parameters for each of a pluralityof MRS configurations. The activation command indicates that at least afirst one of the MRS configurations is to be used by the wireless deviceby including an index identifying the first MRS configuration from amongthe MRS configurations.

According to some embodiments, a method in one or more network nodes ofa wireless communication system comprises sending, to a wireless deviceoperating in the wireless communication system, MRS configurationinformation. The MRS configuration information specifies one or moreparameters for each of a plurality of MRS configurations. The methodthen includes subsequently sending, to the wireless device, anactivation command indicating that at least a first one of the MRSconfigurations is to be used by the wireless device. The activationcommand includes an index identifying the first one of the MRSconfigurations from among the plurality of MRS configurations.

According to some embodiments, a method in a wireless device operatingin a wireless communication system includes receiving, from a networknode in the wireless communication system, MRS configurationinformation. The MRS configuration information specifies one or moreparameters for each of a plurality of MRS configurations. The methodincludes subsequently receiving, from a network node in the wirelesscommunication system, an activation command indicating that at least afirst one of the MRS configurations is to be used by the wirelessdevice. The activation command includes an index identifying the firstone of the MRS configurations from among the plurality of MRSconfigurations. The method also includes searching for at least one MRSspecified by the first one of the MRS configurations, responsive to theactivation command, and performing at least one measurement on the atleast one MRS.

According to some embodiments, one or more network nodes of anarrangement in a wireless communication system each include atransceiver circuit configured to communicate with a wireless device anda processing circuit operatively associated with the transceivercircuit. One or more processing circuits of the one or more networknodes are configured to send, to a wireless device operating in thewireless communication system, MRS configuration information. The MRSconfiguration information specifying one or more parameters for each ofa plurality of MRS configurations. The one or more processing circuitsare also configured to subsequently send, to the wireless device, anactivation command indicating that at least a first one of the MRSconfigurations is to be used by the wireless device. The activationcommand includes an index identifying the first one of the MRSconfigurations from among the plurality of MRS configurations.

According to some embodiments, a wireless device in a wirelesscommunication system includes a transceiver circuit configured tocommunicate with a network node and a processing circuit operativelyassociated with the transceiver circuit. The processing circuit isconfigured to receive, from the network node in the wirelesscommunication system, MRS configuration information. The MRSconfiguration information specifying one or more parameters for each ofa plurality of MRS configurations. The processing circuit is configuredto subsequently receive, from a network node in the wirelesscommunication system, an activation command indicating that at least afirst one of the MRS configurations is to be used by the wirelessdevice. The activation command includes an index identifying the firstone of the MRS configurations from among the plurality of MRSconfigurations. The processing circuit is configured to search for atleast one MRS specified by the first one of the MRS configurations,responsive to the activation command, and performing at least onemeasurement on the at least one MRS.

Further aspects of the present invention are directed to an apparatus,computer program products or computer readable storage mediumcorresponding to the methods summarized above and functionalimplementations of the above-summarized network nodes and wirelessdevice. Of course, the present invention is not limited to the abovefeatures and advantages. Those of ordinary skill in the art willrecognize additional features and advantages upon reading the followingdetailed description, and upon viewing the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates downlink measurement based handover.

FIG. 2 illustrates uplink measurement based handover.

FIG. 3 is a block diagram illustrating a network node, according to someembodiments of the present invention.

FIG. 4 is a process flow diagram showing an example method, according tosome embodiments.

FIG. 5 is a block diagram illustrating a wireless device, according tosome embodiments.

FIG. 6 is a process flow diagram showing another example method,according to some embodiments.

FIGS. 7A-7B illustrate an example embodiment for two-level MRSconfiguration.

FIG. 8 is a block diagram of a functional implementation of anarrangement of one or more network nodes, according to some embodiments.

FIG. 9 is a block diagram of a functional implementation of a wirelessdevice, according to some embodiments.

DETAILED DESCRIPTION

Embodiments of the present invention provide a more efficient signalingprocedure for handling MRS configuration and activation using two-levelsignaling. The two-level MRS configuration includes (1) slow (L3)configuration, where RRC protocol is used to configure the UE with a setof MRSs, and (2) fast (L2) configuration, where Medium Access Control(MAC) protocol is used to activate or deactivate a specific element ofthe RRC-configured MRS set for a UE, by the use of indexing instead ofthe use of actual MRS information. The network decision may be based ona vendor implementation specific algorithm. For example, the network mayavoid unnecessary MRS measurement or measurement reporting in order tosave energy or minimize signaling.

The terms “mobility reference signal”, “measurement reference signal”and “MRS,” as used herein, refer to signals that are transmitted in awireless network and that are specifically designated for measurementsby wireless devices, where the measurements are for use in mobilityprocedures, e.g., handovers from one node to another or from one beam toanother. The MRS could be similar in design and/or purpose as a cellspecific synchronization signal, such as a Primary SynchronizationSignal (PSS) and a Secondary Synchronization Signal (SSS) used in LTE.The term “MRS configuration” refers to a set of parameters that definesthe physical resources occupied by a transmitted MRS, i.e., thetime-frequency and/or code resources, and/or that defines a signalsequence, such as a sequence of symbol values that make up the MRS.Thus, for example, different MRS configurations may specify differenttime-frequency resources for different MRS s, such as different patternsof resource elements in an Orthogonal Frequency-Division Multiplexing(OFDM) time-frequency grid. Different MRS configurations may instead oradditionally specify different sequences of symbol values, for example.In some cases, MRS configurations may indicate search spaces,measurement gaps and/or measurement periodicities.

The techniques described herein allow the MRS configuration to beaccess-node-agonistic. In other words, the UE need not know to whichaccess nodes these configured MRS signals are physically mapped.Therefore, this allows MRSs to be modified in a transparent way to theUE and without transmitting an L3 message to the UE. This is especiallybeneficial when the UE may not have a sufficient time budget to bereconfigured in the RRC level for an MRS modification or a configurationof a new MRS. The embodiments described herein enable the UE to onlymeasure MRSs when needed and then only on those that are interestinggiven that specific UE position (i.e., a UE need not measure on allconfigured MRSs). The techniques use less signaling overhead formobility and provide a faster procedure, thus addressing availabilityand seamless mobility requirements of 5G. The embodiments also support asplit architecture where the delay between baseband processing functions(BPFs) is very short, but the delay between BPF and Radio ControlFunction (RCF) can be significantly higher since it can be placed faraway from the BPFs.

FIG. 3 illustrates a diagram of a network node 30 that can representeach network node of one or more network nodes of an arrangement in awireless communication system. The network node 30 may be, for example,a network access node such as a base station or eNodeB. The network node30 provides an air interface to a wireless device, e.g., an LTE airinterface or WLAN air interface for downlink transmission and uplinkreception, which is implemented via antennas 34 and a transceivercircuit 36. The transceiver circuit 36 may include transmitter circuits,receiver circuits, and associated control circuits that are collectivelyconfigured to transmit and receive signals according to a radio accesstechnology, for the purposes of providing cellular communication, orWLAN services if necessary. According to various embodiments, cellularcommunication services may be operated according to any one or more ofthe 3GPP cellular standards, GSM, GPRS, WCDMA, HSDPA, LTE andLTE-Advanced. The network node 30 may also include communicationinterface circuits 38 for communicating with nodes in the core network,other peer radio nodes, and/or other types of nodes in the network.

The network node 30 also includes one or more processing circuits 32that are operatively associated with and configured to control thecommunication interface circuit(s) 38 and/or the transceiver circuit 36.The processing circuit 32 comprises one or more digital processors 42,e.g., one or more microprocessors, microcontrollers, Digital SignalProcessors (DSPs), Field Programmable Gate Arrays (FPGAs), ComplexProgrammable Logic Devices (CPLDs), Application Specific IntegratedCircuits (ASICs), or any combination thereof. More generally, theprocessing circuit 32 may comprise fixed circuitry, or programmablecircuitry that is specially configured via the execution of programinstructions implementing the functionality taught herein, or maycomprise some combination of fixed and programmable circuitry. Theprocessor(s) 42 may be multi-core.

The processing circuit 32 also includes a memory 44. The memory 44, insome embodiments, stores one or more computer programs 46 and,optionally, configuration data 48. The memory 44 provides non-transitorystorage for the computer program 46 and it may comprise one or moretypes of computer-readable media, such as disk storage, solid-statememory storage, or any combination thereof. By way of non-limitingexample, the memory 44 may comprise any one or more of SRAM, DRAM,EEPROM, and FLASH memory, which may be in the processing circuit 32and/or separate from the processing circuit 32. In general, the memory44 comprises one or more types of computer-readable storage mediaproviding non-transitory storage of the computer program 46 and anyconfiguration data 48 used by the node 30. Here, “non-transitory” meanspermanent, semi-permanent, or at least temporarily persistent storageand encompasses both long-term storage in non-volatile memory andstorage in working memory, e.g., for program execution.

In some embodiments, each of one or more network nodes of an arrangementin a wireless communication system is configured to function as thenetwork node 30. Accordingly, in some embodiments, one or moreprocessing circuits 32 of the one or more network nodes 30 areconfigured to send, to a wireless device 50 operating in the wirelesscommunication system, MRS configuration information, where the MRSconfiguration information specifies one or more parameters for each of aplurality of MRS configurations. The one or more processing circuits ofthe one or more network nodes 30 are configured to subsequently send, tothe wireless device 50, an activation command indicating that at least afirst one of the MRS configurations is to be used by the wireless device50, where the activation command includes an index identifying the firstone of the MRS configurations from among the plurality of MRSconfigurations. That is, in some cases, one network node may send theMRS configuration information and a different network node may send theactivation command.

Regardless of its specific implementation details, the one or moreprocessing circuits 32 of the one or more network nodes 30 areconfigured to perform a method according to one or more of thetechniques described above, such as method 400 of FIG. 4. The method 400includes sending, to a wireless device 50 operating in the wirelesscommunication system, MRS configuration information, the MRSconfiguration information specifying one or more parameters for each ofa plurality of MRS configurations (block 402). The method 400 alsoincludes subsequently sending, to the wireless device 50, an activationcommand indicating that at least a first one of the MRS configurationsis to be used by the wireless device, the activation command includingan index identifying the first one of the MRS configurations from amongthe plurality of MRS configurations (block 404).

In some embodiments, the sending 402 of the MRS configurationinformation is performed using a Radio Resource Configuration (RRC)protocol and the sending 404 of the activation command is performedusing a medium access control (MAC) protocol.

The method 400 may include sending, to the wireless device 50, adeactivation command indicating that the wireless device 50 is to stopusing a second one of the MRS configurations, the deactivation includingan index identifying the second one of the MRS configurations from amongthe plurality of MRS configurations. The method 400 may also includereceiving from the wireless device 50, at one of the one or more networknodes 30, a measurement report comprising measurement data for a MRSspecified by the first one of the MRS configurations.

The first one of the MRS configurations may specify a plurality of MRSsto be measured by the wireless device 50, each MRS corresponding to aMRS identifier. Each MRS identifier may correspond to a predeterminedMRS sequence.

In some embodiments, the first one of the MRS configurations specifies asearch space identifier, the search space identifier indicating one of aplurality of transmission resource regions to be used by the wirelessdevice 50 when performing measurements of a MRS specified by the firstone of the MRS configurations. The first one of the MRS configurationsmay specify measurement gaps and/or measurement periodicity.

The sending of the MRS configuration information may be performed by adifferent network node than the network node that sends the activationcommand. For example, the source access node 70 may send the MRSconfiguration information to the UE 50, but it is the target access node80 that sends the indexed activation or deactivation command to the UE50.

FIG. 5 illustrates an example wireless device 50, referred to as UE 50in FIG. 5, that is configured to perform the techniques describedherein. The UE 50 may also be considered to represent any wirelessdevices that may operate in a network. The UE 50 herein can be any typeof wireless device capable of communicating with network node or anotherUE over radio signals. The UE 50 may also be referred to, in variouscontexts, as a radio communication device, a target device, adevice-to-device (D2D) UE, a machine-type UE or UE capable of machine tomachine (M2M) communication, a sensor-equipped UE, a PDA (personaldigital assistant), a wireless tablet, a mobile terminal, a smart phone,laptop-embedded equipment (LEE), laptop-mounted equipment (LME), awireless USB dongle, a Customer Premises Equipment (CPE), etc.

The UE 50 communicates with one or more radio nodes or base stations,such as one or more network nodes 30, via antennas 54 and a transceivercircuit 56. The transceiver circuit 56 may include transmitter circuits,receiver circuits, and associated control circuits that are collectivelyconfigured to transmit and receive signals according to a radio accesstechnology, for the purposes of providing cellular communicationservices.

The UE 50 also includes one or more processing circuits 52 that areoperatively associated with and control the radio transceiver circuit56. The processing circuit 52 comprises one or more digital processingcircuits, e.g., one or more microprocessors, microcontrollers, DSPs,FPGAs, CPLDs, ASICs, or any mix thereof. More generally, the processingcircuit 52 may comprise fixed circuitry, or programmable circuitry thatis specially adapted via the execution of program instructionsimplementing the functionality taught herein, or may comprise some mixof fixed and programmed circuitry. The processing circuit 52 may bemulti-core.

The processing circuit 52 also includes a memory 64. The memory 64, insome embodiments, stores one or more computer programs 66 and,optionally, configuration data 68. The memory 64 provides non-transitorystorage for the computer program 66 and it may comprise one or moretypes of computer-readable media, such as disk storage, solid-statememory storage, or any mix thereof. By way of non-limiting example, thememory 64 comprises any one or more of SRAM, DRAM, EEPROM, and FLASHmemory, which may be in the processing circuit 52 and/or separate fromprocessing circuit 52. In general, the memory 64 comprises one or moretypes of computer-readable storage media providing non-transitorystorage of the computer program 66 and any configuration data 68 used bythe user equipment 50.

Accordingly, in some embodiments, the processing circuit 52 of the UE 50is configured to receive, from a network node 30 in the wirelesscommunication system, MRS configuration information, the MRSconfiguration information specifying one or more parameters for each ofa plurality of MRS configurations. The processing circuit 52 is alsoconfigured to subsequently receive, from a network node in the wirelesscommunication system, an activation command indicating that at least afirst one of the MRS configurations is to be used by the UE 50, theactivation command including an index identifying the first one of theMRS configurations from among the plurality of MRS configurations. Theactivation command may be received from a different network node thanthe network node 30 that sent the MRS configuration information. Theprocessing circuit 52 is also configured to search for at least one MRSspecified by the first one of the MRS configurations, responsive to theactivation command and perform at least one measurement on the at leastone MRS.

Regardless of its specific implementation details, the processingcircuit 52 of the UE 50 is configured to perform a method according toone or more of the techniques described, such as method 600 of FIG. 6.The method 600 includes receiving, from a network node 30 in thewireless communication system, MRS configuration information, the MRSconfiguration information specifying one or more parameters for each ofa plurality of MRS configurations (block 602). The method 600 includessubsequently receiving, from a network node in the wirelesscommunication system, an activation command indicating that at least afirst one of the MRS configurations is to be used by the UE 50, theactivation command including an index identifying the first one of theMRS configurations from among the plurality of MRS configurations (block604). The method 600 also includes searching for at least one MRSspecified by the first one of the MRS configurations, responsive to theactivation command (block 606) and performing at least one measurementon the at least one MRS (block 608).

In some embodiments, the receiving of the MRS configuration informationis performed using an RRC protocol, and the receiving of the activationcommand is performed using a MAC protocol.

The method 600 may further include receiving a deactivation commandindicating that the UE 50 is to stop using a second one of the MRSconfigurations, the deactivation including an index identifying thesecond one of the MRS configurations from among the plurality of MRSconfigurations and discontinuing measurements of at least one MRSspecified by the second one of the MRS configurations. The method 600may include sending a measurement report including measurement data fora MRS specified by the first one of the MRS configurations.

In some embodiments, the first one of the MRS configurations specifies aplurality of MRSs to be measured by the UE 50, each MRS corresponding toa MRS identifier. The first one of the MRS configurations may specify asearch space identifier. The search space identifier indicates one of aplurality of transmission resource regions to be used by the UE 50 whenperforming measurements of a MRS specified by the first one of the MRSconfigurations. The searching for at least one MRS specified by thefirst one of the MRS is performed using the indicated transmissionresource region. The first one of the MRS configurations may specifymeasurement gaps and/or measurement periodicity.

FIGS. 7A and 7B shown an example embodiment of an arrangement 10 fortwo-level MRS configuration in a wireless communication system. In thisexample, the source access node 70 and/or the target access node 80 areconfigured to perform MRS configuration and activation using two layers,L3 and L2, as described for the one or more network nodes 30 of thearrangement 10. The L3 Control 90, which may be located in thecentralized part of the RAN (e.g., remote control unit/radio controlfunction (RCU/RCF) in the 5G context), has the configuration andplanning responsibility of MRSs. As shown by step 1 in both FIGS. 7A and7B, the L3 Control 90 configures the UE 50 with a set of MRSconfigurations and conveys the MRS configurations by means of L3signaling (e.g., using the RRC protocol). At step 2 or otherwise, userdata is exchanged between the UE 50 and the source access node 70, witha baseband processing function in the source access node 70 forwardinguser data to and receiving user data from a packet processing function(PPF).

The source and target access nodes 70, 80 request and confirm MRSassignment and activation at steps 3 and 4. This part of the procedureis transparent to the UE.

At step 5, L2 signaling (MAC protocol) is used to activate or deactivatea specific MRS configuration of the RRC-configured MRS set for the UE 50by indicating the index of the respective MRS, instead of calling withthe complete MRS configuration information. The activation (anddeactivation) of a particular MRS configuration or set of MRSconfigurations may be handled at Layer 2 (L2), i.e., the MAC layer,which, in an access node having a distributed architecture, may beimplemented in a distributed node close to the access node's antenna(s),e.g., in the access node's baseband processing unit/baseband processingfunction (BPU/BPF), in the 5G context. This allows for a faster controlof MRS activation and deactivation, relative to the relatively slowRRC-based configuration procedures. This is not only quicker, but savescontrol information bits.

Since the BPU will be able to handle mobility locally, the possibilityof sending a set of MRS configurations to the UE in advance, and thenselectively telling the UE 50 which MRS to search for is advantageous.With this introduced flexibility at the BPU, MRSs can be configured in asmart way when performing mobility, such as deciding how and when toreuse the MRSs. For example, one or more network nodes 30 may activateany of the UE-configured MRSs and tell the UE 50 to search for itwithout involving RRC and the roundtrip delays it would cause.

By using faster L2 signaling with MRS indexes for activation ordeactivation, the UE 50 also saves energy by not searching for allconfigured MRSs continuously. Yet, the option to either constantlysearch by UE or only search when activated may be a configuration optionin the RRC message as well as a part of the slower (L3) MRSconfiguration.

According to the techniques described herein, the source access node 70can proactively configure the UE 50 for a set of MRSs by means of an L3MRS configuration message. The actual assignment and activation of MRSscan later be negotiated between the source access node 70 and the targetaccess node 80 in a way transparent to the UE 50. Since the particularMRS to be used by the UE 50 can simply be indexed by the L2 activationmessage, instead of re-involving the L3 configuration, the UE 50 canmeasure and get synched with the target access node 80 faster. The RRCsignaled list of MRS configurations could be, for instance, illustratedby Table 1.

TABLE 1 Index List of MRS IDs Search space ID 1 1, 2, 3, 4 1 2 3, 4 2 31, 2 2 . . .

In some embodiments, there may be a set of standardized MRS sequencesthat are identified in the list by an MRS ID. Similarly, there may be alist of search spaces in the specifications, which are identified in thelist by a search space ID. The measurement activation on the MAC levelthen includes an index value pointing to a certain row of a table thathas been configured in the UE 50, e.g., the table shown in Table 1. Thetable can be fairly long, so as to include a wide variety ofcombinations of MRS signals and, optionally, search spaces, but since itcan be signaled to the UE 50 long before the handover, it can besignaled at a point where the UE 50 is in the middle of a beam and thesignal is strong, so that the relative signaling cost becomes small.

As discussed in detail above, the techniques described herein, e.g., asillustrated in the process flow diagrams of FIGS. 4 and 6, may beimplemented, in whole or in part, using computer program instructionsexecuted by one or more processors. It will be appreciated that afunctional implementation of these techniques may be represented interms of functional modules, where each functional module corresponds toa functional unit of software executing in an appropriate processor orto a functional digital hardware circuit, or some combination of both.

FIG. 8 illustrates an example functional module or circuit architectureas may be implemented in an arrangement 10 of one or more network nodes30 of a wireless communication system. The implementation includes anMRS configuration module 802 for sending, to a wireless device operatingin the wireless communication system, MRS configuration information, theMRS configuration information specifying one or more parameters for eachof a plurality of MRS configurations. The implementation also includesan activation module 804 for subsequently sending, to the wirelessdevice, an activation command indicating that at least a first one ofthe MRS configurations is to be used by the wireless device, theactivation command including an index identifying the first one of theMRS configurations from among the plurality of MRS configurations. Theactivation module 804 may also be located in another network node.

Similarly, FIG. 9 illustrates an example functional module or circuitarchitecture as may be implemented in a wireless device of a wirelesscommunication system, such as UE 50. The implementation includes an MRSconfiguration module 902 for receiving, from a network node in thewireless communication system, MRS configuration information, the MRSconfiguration information specifying one or more parameters for each ofa plurality of MRS configurations. The implementation also includes anactivation module 904 for subsequently receiving, from a network node inthe wireless communication system, an activation command indicating thatat least a first one of the MRS configurations is to be used by thewireless device, the activation command including an index identifyingthe first one of the MRS configurations from among the plurality of MRSconfigurations. The implementation includes a search module 906 forsearching for at least one MRS specified by the first one of the MRSconfigurations, responsive to the activation command and a measurementmodule 908 for performing at least one measurement on the at least oneMRS.

Notably, modifications and other embodiments of the disclosedinvention(s) will come to mind to one skilled in the art having thebenefit of the teachings presented in the foregoing descriptions and theassociated drawings. Therefore, it is to be understood that theinvention(s) is/are not to be limited to the specific embodimentsdisclosed and that modifications and other embodiments are intended tobe included within the scope of this disclosure. Although specific termsmay be employed herein, they are used in a generic and descriptive senseonly and not for purposes of limitation.

What is claimed is:
 1. A method, in one or more network nodes of a wireless communication system, the method comprising: sending, to a wireless device operating in the wireless communication system, an activation command indicating that an identified first one of a plurality of mobility or measurement reference signal (MRS) configurations is to be used by the wireless device.
 2. The method of claim 1, wherein the sending of the activation command is performed using a medium access control (MAC) protocol.
 3. The method of claim 2, further comprising sending to the wireless device, prior to sending the activation command, MRS configuration information specifying the one or more parameters for each of one or more of the plurality of MRS configurations.
 4. The method of claim 3, wherein the sending of the MRS configuration information is performed by a different network node than the sending of the activation command.
 5. The method of claim 3, wherein the sending of the MRS configuration information is performed using a Radio Resource Configuration (RRC) protocol.
 6. The method of claim 1, further comprising sending, to the wireless device, a deactivation command identifying a second one of the MRS configurations from among the plurality of MRS configurations, the deactivation command indicating that the wireless device is to stop using the second one of the MRS configurations.
 7. The method of claim 1, further comprising receiving from the wireless device, at one of the one or more network nodes, a measurement report comprising measurement data for a MRS specified by the first one of the MRS configurations.
 8. The method of claim 1, wherein the first one of the MRS configurations specifies a plurality of MRS's to be measured by the wireless device, each MRS corresponding to a MRS identifier.
 9. The method of claim 8, wherein each MRS identifier corresponds to a predetermined MRS sequence.
 10. The method of claim 1, wherein the first one of the MRS configurations specifies a search space identifier, the search space identifier indicating one of a plurality of transmission resource regions to be used by the wireless device when performing measurements of a MRS specified by the first one of the MRS configurations.
 11. The method of claim 1, wherein the first one of the MRS configurations specifies one or more of: measurement gaps; and measurement periodicity.
 12. A method, in a wireless device operating in a wireless communication system, the method comprising: receiving, from a network node in the wireless communication system, an activation command indicating that an identified first one of a plurality of mobility or measurement reference signal (MRS) configurations is to be used by the wireless device; and performing at least one measurement on at least one MRS specified by the first one of the MRS configurations.
 13. The method of claim 12, wherein the receiving of the activation command is performed using a medium access control (MAC) protocol.
 14. The method of claim 13, further comprising receiving, prior to receiving the activation command, MRS configuration information specifying the one or more parameters for each of one or more of the plurality of MRS configurations.
 15. The method of claim 14, wherein the receiving of the MRS configuration information is from a different network node than the receiving of the activation command.
 16. The method of claim 14, wherein the receiving of the MRS configuration information is performed using a Radio Resource Configuration (RRC) protocol.
 17. The method of claim 12, further comprising: receiving a deactivation command identifying a second one of the MRS configurations from among the plurality of MRS configurations, the deactivation command indicating that the wireless device is to stop using the second one of the MRS configurations; and discontinuing measurements of at least one MRS specified by the second one of the MRS configurations.
 18. The method of claim 12, wherein the method further comprises sending a measurement report including measurement data for an MRS specified by the first one of the MRS configurations.
 19. The method of claim 12, wherein the first one of the MRS configurations specifies a plurality of MRS's to be measured by the wireless device, each MRS corresponding to an MRS identifier.
 20. The method of claim 12, wherein the first one of the MRS configurations specifies a search space identifier, the search space identifier indicating one of a plurality of transmission resource regions to be used by the wireless device when performing measurements of a MRS specified by the first one of the MRS configurations, and wherein the searching for the at least one MRS specified by the first one of the MRS configurations is performed using the indicated transmission resource region.
 21. The method of claim 12, wherein the first one of the MRS configurations specifies one or more of: measurement gaps; and measurement periodicity.
 22. An arrangement of one or more network nodes of a wireless communication system, wherein each of the one or more network nodes comprises: a transceiver circuit configured to communicate with a wireless device operating in the wireless communication system; and a processing circuit operatively associated with the transceiver circuit, wherein one or more processing circuits of the one or more network nodes are configured to: send, to a wireless device operating in the wireless communication system, an activation command indicating that an identified first one of a plurality of mobility or measurement reference signal (MRS) configurations is to be used by the wireless device.
 23. The arrangement of claim 22, wherein the one or more processing circuits are configured to send to the wireless device, prior to sending the activation command, MRS configuration information specifying the one or more parameters for each of one or more of the plurality of MRS configurations, and wherein the one or more processing circuits are configured to send the MRS configuration information using a Radio Resource Configuration (RRC) protocol and send the activation command using a medium access control (MAC) protocol.
 24. A wireless device of a wireless communication system, comprising: a transceiver circuit configured to communicate with one or more network nodes operating in the wireless communication system; and a processing circuit operatively associated with the transceiver circuit and configured to: receive, from a network node in the wireless communication system, an activation command indicating that an identified first one of a plurality of mobility or measurement reference signal (MRS) configurations is to be used by the wireless device; and perform at least one measurement on at least one MRS specified by the first one of the MRS configurations.
 25. The wireless device of claim 24, wherein the processing circuit is configured to receive, prior to receiving the activation command, MRS configuration information specifying the one or more parameters for each of one or more of the plurality of MRS configurations, and wherein the processing circuit is further configured to receive the MRS configuration information using a Radio Resource Configuration (RRC) protocol and receive the activation command using a medium access control (MAC) protocol. 